JP7103677B2 - Drill screws for thin metal plates and structures and fixing devices using them - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act Published by the catalog issued by the applicant on August 3, 2nd year of Reiwa

The present invention relates to a drill screw for a thin metal plate, a structure constructed by using the drill screw, and a fixing device. Here, the thin metal plate means a metal plate (mainly a steel plate or a stainless plate) of 1.6 mm or less, and the structure includes a roof portion, a ceiling portion, a wall portion, and the like of a building.

There are many buildings that use steel plate base materials with a thickness of about 1 to 2 mm, and it is widely practiced to fix heat insulating materials and control panel materials to these base materials with self-drilling screws such as drill screws. It has been. For example, the waterproof sheet and heat insulating material are fixed to the upper surface of the deck plate (folded plate) that constitutes the roof of the building with drill screws and tapping screws , and the heat insulating material and interior are attached to the columns and beams made of shaped steel such as C type. It is widely practiced to fix the material with a drill screw.

Then, in the drill screw, it has been proposed or implemented to form a notch groove such as a V shape extending in the axial direction by dividing the screw thread entirely or partially in the threaded portion. As an example, Patent Document 1 discloses that a plurality of recesses (notch grooves) parallel to the axis are formed in a tapered threaded portion of the threaded portion closer to the drill portion. It is stated that the screwing torque can be reduced by the dent. Therefore, in Patent Document 1, it is understood that the dent is provided for the effect of improving the machinability of the thin metal plate.

On the other hand, Patent Document 2 also discloses that a V-shaped notch groove (notch line) is formed. In this Patent Document 1, the presence of the notch line improves the discharge of chips, and the base material. It is stated that a smooth cut can be realized. Therefore, in Patent Document 2, as in Patent Document 1, it can be said that the notch line is provided for the effect of improving the machinability of the thin metal plate. Also in wood screws, notch grooves are formed in order to improve machinability and chip evacuation.

Japanese Unexamined Patent Publication No. 2006-177436 JP-A-2017-67179

In buildings and structures, it is widely practiced to fix a work such as a heat insulating material to a structural material made of a thin metal plate such as a deck plate with a drill screw. One of the problems in this case is a screw to the structural material. Since the catching allowance of the mountain is small, if the screwing torque is too strong, a stripping phenomenon occurs in which the female screw of the structural material is crushed, and the drill screw spins idle, which may make it meaningless as a screw.

Another problem is the loosening of the drill screw that occurs after fastening. There are many causes of looseness. For example, the wind may push the work away from the structural material. When vibration acts on the drill screw by repeating the movement that the work is elastically deformed by the wind pressure and returned by the elastic restoring force, the drill screw tends to loosen at an accelerating rate. Loosening may also occur when the vibration of the air conditioner travels through the structural material and acts on the drill screw. It should be noted that the looseness and the idling at the time of construction are inextricably linked to each other, and both of them are caused by the fact that the thread is not easily caught by the structural material.

Regarding this point, Patent Document 1 states that the inner peripheral portion of the prepared hole is 2.5 times the plate thickness by pressing the prepared hole with a protruding angle portion (rib) provided on the valley surface of the tapered threaded portion. It is explained that it can be expanded to a certain thickness.

As described in Patent Document 1, if the inner peripheral portion of the prepared hole can be partially thickened, the catching allowance between the screw thread and the thin metal plate can be remarkably increased, so that high fastening strength can be ensured. At the same time, it can be said that the phenomenon that the threaded portion runs idle can be avoided.

The present invention has been made against the background of such a situation, and secures high fastening strength while suppressing screwing resistance, and secures a high loosening prevention effect, and prevents idling of the threaded portion during construction. This is an attempt to easily realize this with a technique from a viewpoint different from that of Patent Document 1.

The invention of the present application includes various configurations, and a typical example thereof is specified in each claim. Of these, the invention of claim 1 relates to a self-perforated screw for a thin metal plate, and the self-perforated screw is
" A drill screw for fixing a work to a thin metal plate with a thickness of 1.6 mm or less.
It includes a shaft having a threaded portion made of a thread, a drill portion provided at the tip of the shaft , and a head provided at the base end of the shaft.
In the threaded portion, a group of notch grooves that divide the thread completely or partially is divided in the circumferential direction to form a plurality of rows, and the notch grooves are formed behind the valley bottom with the valley bottom in between. The positioned advancing end face functions as a cutting edge for the thin metal plate. "
It has a basic structure.

And in the above basic configuration
"In the threaded portion, a band-shaped valley surface is formed in the valley portion between adjacent threads, and the valley diameter of the threaded portion is larger than the inner diameter of the pilot hole formed in the thin metal plate by the drill portion. While having a large diameter or the same diameter,
When the width dimension of the valley surface is E, the pitch of the threads is P, and the plate thickness of the thin metal plate is t , the state of being screwed into the thin metal plate by setting E <t <P. Then, on one side sandwiching the axial center, the inner peripheral portion of the thin metal plate fits tightly into the valley portion, and on the other side sandwiching the axial center, the inner peripheral surface of the pilot hole in the thin metal plate. The screw thread is set to bite into the
The axial distance between the notch grooves adjacent to each other in the circumferential direction is smaller than the thickness of the thin metal plate, and in a state where the screw portion is screwed into the thin metal plate, among the threads. At least one notch groove is set to overlap the inner peripheral surface of the pilot hole in the thin metal plate. "
It is configured as.

The notch groove may be positioned up to the valley surface and the thread may be completely divided by the notch groove, or the notch groove may be located at the midway height of the thread.

The invention of claim 2 is an example of development of claim 1.
"The angle formed by the plane orthogonal to the axis and the flank on the advancing side of the thread is θ1, and the angle formed by the plane orthogonal to the axis and the flank on the trailing side of the thread is θ2. In relation to each other, θ1 + θ2 is set to 35 to 45 °.
Further, when the axial distance between the bottoms of the notch grooves in the adjacent threads is L, L and the t are the same or set to t> L. "
It is configured as.

The invention of claim 3 embodies claim 1 or 2.
"The thin metal plate and the screw thread have a plurality of notch grooves within the thickness range of the thin metal plate within a half circumference in a state where the screw portion is screwed into the thin metal plate. Set in relationship "
It is configured as.

The present invention also includes a structure, and as claimed in claim 4, this structure is:
"It is provided with a structural material made of a thin metal plate having a thickness of 1.6 mm or less, a work that overlaps the structural material , and a drill screw that presses and fixes the work to the thin metal plate.
The drill screw includes a shaft having a screw portion made of a screw thread, a drill portion provided at the tip of the shaft , and a head provided at the base end of the shaft, and the screw portion has a screw thread. A group of notch grooves that divide the whole or a part of the notch groove is divided in the circumferential direction to form a plurality of rows , and the advancing side end face of the notch grooves located behind the screwing direction across the valley bottom is the thin portion. It functions as a cutting edge for metal plates. "
It is a basic configuration.

And in the above basic configuration
"In the threaded portion, a band-shaped valley surface is formed in the valley portion between adjacent threads, and the valley diameter of the threaded portion is larger than the inner diameter of the pilot hole formed in the thin metal plate by the drill portion. While having a large diameter or the same diameter,
When the width dimension of the valley surface is E, the pitch of the threads is P, and the plate thickness of the thin metal plate is t , the state of being screwed into the thin metal plate by setting E <t <P. Then, on one side sandwiching the axial center, the inner peripheral portion of the thin metal plate fits tightly into the valley portion, and on the other side sandwiching the axial center, the inner peripheral surface of the pilot hole in the thin metal plate. The screw thread is set to bite into the
The axial distance between the notch grooves adjacent to each other in the circumferential direction is smaller than the thickness of the thin metal plate, and in a state where the screw portion is screwed into the thin metal plate, among the threads. At least one notch groove is set to overlap the inner peripheral surface of the pilot hole in the thin metal plate. "
It is configured as.

In many cases, the thread has a triangular cross section, and a grooved thread (or a two-hump type thread) in which one thread has two ridges and a spiral groove is formed in the thread is also assumed. However, the present invention also includes such a grooved thread. In the case of this grooved thread, it is also possible to form a notch groove only at the trailing flank or only at the advancing flank.

The present invention also includes a fixing device relating to a combination of a self-perforated screw and a washer, and this fixing device is as described in claim 5.
"It is composed of the drill screw and the washer according to any one of claims 1 to 3, and the seating surface of the head of the drill screw is formed in a tapered shape with a narrowed lower portion and a polygonal flat cross section. On the other hand, the washer is formed with a flat-section polygonal lower narrowed tapered receiving seat in which the seating surface of the head of the drill screw is in close contact, and the receiving seat is not divided by a slit. It is continuous in a series in the circumferential direction. "
It is configured as.

In this case, it is preferable that the number of angles of the seating surface of the screw head and the receiving seat of the washer is the same as the number of notched grooves of the screw. The fixing device of claim 5 is used for fixing a work that is compressively deformed against elasticity. In this case, the work may be a single layer or a multi-layer, but in the case of a multi-layer, it is sufficient if at least one layer is elastically deformed.

When the threaded portion is screwed into the thin metal plate, an external force is applied to the thin metal plate in the front and back directions due to the screw thread, so that the inner peripheral portion of the thin metal plate tends to bend and deform in the front and back directions. If the thickness of the thin metal plate is smaller than the root width of the threaded portion, or the root diameter of the threaded portion is larger than the inner diameter of the pilot hole created by the self-perforated portion, the inner peripheral portion of the thin metal plate is oriented in the front and back directions. Since the thread easily escapes and deforms, the thread bites into the inner peripheral portion of the prepared hole only slightly, a stripping phenomenon occurs, the thread portion tends to run idle, and the fastening strength and the loosening prevention effect tend to be insufficient. ..

On the other hand, in the present invention, first, since the root diameter of the threaded portion is larger than or the same diameter as the prepared hole, the prepared hole can be expanded by the valley portion of the shaft, and thus is thin. It is possible to tightly mesh the inner peripheral portion of the metal plate with the screw portion in a state where bending and deformation in the front and back directions are regulated.

Further, since the width dimension E of the valley surface, the pitch P of the threads, and the plate thickness t of the thin metal plate have a relationship of E <t <P, the inner circumference of the pilot hole of the thin metal plate is formed. The flesh of the portion loses a refuge and escapes to the outside of the radius, so that the inner peripheral portion of the prepared hole can be thickened at least partially. Specifically, since the resistance to the pilot hole is usually non-uniform in the circumferential direction, the inner peripheral portion of the thin metal plate fits firmly into the valley portion of the threaded portion on one side of the axial center. On the other side of the axis, the inner peripheral part tends to be thickened about half a circumference, and one or more threads bite into this thickened part. .. Depending on the size of the plate thickness t with respect to the valley width, a thick portion may be formed over the entire circumference.

In other words, in the inner peripheral part of the thin metal plate, the escape deformation in the front and back directions is restricted, so that at least a part of the inner peripheral part in the circumferential direction becomes thicker and the screw thread bites firmly. This makes it possible to improve the catching property of the thread on the prepared hole, prevent the female screw on the inner circumference of the prepared hole from being crushed and the threaded part from spinning (stripping phenomenon), as well as high fastening strength and looseness. A stopping effect can be obtained.

Since at least one notch groove formed in the threaded portion overlaps the inner peripheral surface of the prepared hole, the notch groove is screwed in by the cutting edge action of the advancing side end face facing the screwing direction. The resistance can be suppressed, and the force required for screwing can be reduced accordingly. Therefore, it is possible to reduce the burden on the operator while ensuring high fastening strength. Further, since the trailing end face of the notch groove facing the screw return direction acts as a resistance against screwing back, the notch groove can improve the effect of preventing loosening.

In this case, as in the embodiment, the notch groove is tilted from the start end to the end in the direction opposite to the screwing direction (that is, the spiral direction of the notch groove and the spiral direction of the screw thread are in the same direction). When tilted to, the inner peripheral portion of the prepared hole is pushed downward (in the direction of the tip) by the chasing end face of the notch groove, so that there is an advantage that the resistance to screwing back can be increased and the loosening prevention effect can be promoted.

If the angle of the screw thread is about 60 ° like a normal machine screw, the thin metal plate must be widely spread in both the front and back directions in order to bite into the thin metal plate. The biteability may deteriorate or the screwing resistance may increase. However, if the thread angle is set to about 35 to 45 ° as in claim 2 of the present application, the biting property to the thin metal plate is improved. , The function of forming female threads in the pilot holes of thin metal plates is improved.

Further, since the inclination angle of the trailing flank is smaller than the tilting angle of the advancing flank, the screwing resistance can be reduced as compared with the case where the angle of the advancing flank and the angle of the chasing flank are the same, and vice versa. The resistance to rotation can be increased. Therefore, it is possible to achieve both ease of screwing and improvement of the loosening prevention function.

Further, as described as the effect of claim 1, in the present invention, a phenomenon that the inner peripheral portion of the thin metal plate is partially thickened occurs , and the screw thread bites into the prepared hole is ensured. If the distance L between the edges of the adjacent notch grooves is the same as or t> L as the plate thickness t of the thin metal plate as in claim 2, the thin metal plate fits into the valley of the threaded portion. When it is inserted, it is possible to make it easier for the adjacent notch grooves to bite into the thin metal plate. As a result, the effect of preventing loosening due to catching of the notch groove can be improved.

As described above, in the notch groove, when screwing, the advancing side end face facing the screwing direction acts as a cutting edge, so that the biting property to the thin metal plate can be improved and the screwing resistance can be suppressed, while the screwing resistance can be suppressed. The chasing end face of the notch groove acts as a resistance against reverse rotation to exert a locking effect. However, when the configuration of claim 3 is adopted, the screw portion of the inner peripheral portion of the thin metal plate is screwed. Since there are a plurality of notch grooves in the thickened portion due to the above, the effect of the notch grooves can be promoted. The number of notched grooves is preferably about 3 or 4 in about half a circumference. Therefore, it can be said that the number of notched grooves is preferably at least 5 in the circumferential direction.

As a means for preventing the screw from loosening, it has been proposed to form a protrusion on the seating surface of the screw head, while forming an engaging groove on the receiving seat of the washer so that the protrusion is fitted into the engaging groove. However, in this case, the loosening prevention function is carried out only by the receiving seat of the washer, and the receiving seat is divided by the engaging groove and easily deformed, so that the loosening prevention effect is limited.

On the other hand, when the configuration of claim 5 of the present application is adopted, when the screw tries to loosen, the entire washer must be pushed into the work to greatly elastically deform the work, so that the resistance to the loosening of the screw becomes remarkably high. That is, the elastic resistance of the work can be used to prevent the screws from loosening. Therefore, the anti-loosening effect can be significantly improved.

In claim 5, when the number of angles of the seat surface and the receiving seat is matched with the number of notched grooves as in the embodiment, the loosening prevention function of the notch groove and the loosening prevention function of the square receiving seat are synergistic. , There is an advantage that the loosening prevention effect can be further improved.

In the figure showing the embodiment, (A) is a front view in which most of the notched grooves are omitted, (B) is an overall side view (photograph), (C) is a plan view, and (D) is a partially enlarged view. (E) is a sectional view taken along line EE of (D), and (F) is a partial perspective view (photograph). (A) is a schematic vertical sectional view of the structure, (B) is a vertical sectional view of a main part of the structure, (C) is a vertical sectional view at the initial stage of fastening work, and (D) is a vertical sectional view of the main part in a fully screwed state. The top view, (E) is an enlarged view of the notch groove portion, and (F) is an enlarged view of another example of the notch groove in which the posture is changed. (A) is a perspective view in a screwed state, (B) is a perspective view in a state where the screw portion is removed, and (C) is a perspective view seen from the back side. (A) is a front view of a drill screw of another form, (B) is a perspective view of a screw portion, and (C) is a view showing another example of a thread and a notch groove. It is a figure which shows the fixing device combined with a washer, (A) is a perspective view which looked at the screw from the bottom, (B) is a figure which looked at the washer from the top, (C) is the figure which looked at the washer from the bottom, ( D) is a partial cross-sectional view in a used state, and (E) is a sectional view taken along line EE of (D).

(1). Structure of Drill Screw Next, an embodiment of the present invention will be described with reference to the drawings. This embodiment is applied to a drill screw. The drill screw is made of metal such as steel or stainless steel, and as shown in FIGS. 1A and 1B, the shaft 1 and the drill portion 2 (self-drilling portion) provided at the tip (one end) thereof and the shaft 1 It is composed of a head 3 provided at the base end (the other end), and a threaded portion composed of one thread 4 is formed on the shaft 1. In the following, the upper and lower words are used for convenience to specify the direction, but it is defined that the drill portion 2 is located at the bottom and the head 3 is located at the top. Therefore, the top surface of the head 3 appears in a plan view.

The drill portion 2 has a conventionally known shape, and a pair of vertical grooves 5 are formed to form a pair of cutting edges 6, and a chisel edge is formed at the tip of the drill portion 2. The vertical groove 5 hangs on the tip of the threaded portion, and the starting end of the thread 4 is divided by the vertical groove 5.

The head 3 is a dish type having a downwardly narrowed tapered seating surface, and a quadrangular engaging groove (recess) 7 with which a driver bit (not shown) is engaged is formed on the top surface. The engaging groove 7 may have another shape such as a cross shape. Further, the head 3 can be set to an arbitrary shape depending on the application, such as a hexagonal head, a pan head, or a flat plate type.

As shown in FIG. 1 (D), the screw thread 4 has a ridge line formed on the thread surface, but basically has a triangular cross section (to be exact, the cross section shape is trapezoidal), and the shaft. The angle θ1 formed by the plane orthogonal to the center O and the advancing flank 8 is larger than the angle θ2 formed by the plane orthogonal to the axial center O and the trailing flank 9. For example, θ1 can be set to about 30 to 35 °, and θ2 can be set to about 0 to 10 °. θ1 + θ2 is the angle of the thread 4, and the angle of the thread 4 is set to about 35 to 45 °.

FIG. 1 (D) shows the width dimension (mountain thickness) W of the base of the thread 4 and the height H of the thread 4, but the relationship is W <H (both are). It may be almost the same.) Therefore, the screw thread 4 has a shape that easily bites into the thin metal plate 10 that is the mating material to be screwed.

A band-shaped valley surface 11 exists in the valley portion between the adjacent threads 4. The groove width E of the valley surface 11 is smaller than the maximum width W of the screw thread 4. The outer diameter D1 of the valley surface 11 (see FIG. 2D) is set to be slightly larger than the rotating outer diameter D2 of the drill portion 2 (see FIG. 2B). Therefore, the prepared hole formed in the mating material 10 is expanded and expanded by the valley surface 11. The groove width E of the valley surface 11 is smaller than the plate thickness t of the mating material 10. For example, when the plate thickness t of the mating material 10 is 1.0 mm, the groove width E is set to about 0.8 mm.

It should be noted that the structural materials of buildings are usually standardized by each manufacturer, and the plate thickness is also common in the standards of each company. Therefore, in the present invention, the numerical value is selected according to the standard, which can be applied to many structural materials.

The height of the screw thread 4 is gradually increased from its starting end. Therefore, as shown in FIG. 1A, the threaded portion has a tapered portion 12 in which the height of the thread 4 changes, and the outer diameter of the portion following the tapered portion 12 is constant. It is a straight part.

At the lower part of the neck of the shaft 1, there is an unthreaded portion 13 in which the thread 4 is not formed, but in (B) of FIG. 1, the unthreaded portion 13 is slightly longer than that of (A). Therefore, strictly speaking, (A) and (B) in FIG. 1 cannot be said to be the same, but the presence or absence of the screwless portion 13 and its length are selected according to the application, and the essence of the invention is Since it is an element that does not affect, the embodiment of FIG. 1 (A) and the embodiment of FIG. 1 (B) can be regarded as the same embodiment. As shown as another example in FIG. 4A, there is also a drill screw having a considerably long screwless portion 13 (the notch groove 14 is not specified in FIG. 4A, but the threaded portion is shown in FIG. It has the same form as 1 (A) and (B).) In FIG. 4B, the entire notch groove 14 is displayed.

The screw thread 4 is formed with a plurality of V-shaped notch grooves 14 extending (spotted) in the axial direction in a state of dividing the threads (notch grooves 14 in FIGS. 2C and 2D). 14 is omitted.). In the illustrated form, the depth of the notch groove 14 is lower than the height of the thread 4. Therefore, as shown in FIG. 1 (E), the bottom 14a of the notch groove 14 is located at the mid-height of the thread 4 without reaching the valley surface 11, but the bottom 14a of the notch groove 14 is the valley surface. It may reach 11. The distance L between the edges of the bottoms 14a of the adjacent notch grooves 14 is set to be substantially the same as the plate thickness t of the mating material 10.

The start end of the notch groove 14 starts from the end portion of the tapered portion 12. Therefore, the notch groove 14 is not formed in most of the threads 4 at the tapered portion 12. Further, the notch groove 14 is in a twisted posture (spiral posture) around the axis so as to be inclined in the same direction as the thread 4, and the lead angle with respect to the axis is very small (about half a circumference). It is designed to pass 10 or more peaks due to the twist of.).

When the plate thickness t of the mating material 10 is 1.0 mm, the outer diameter of the thread 4 is about 7 mm, the valley diameter D1 is about 4.2 mm, the pitch P is about 1.8 mm, and the drill. The rotation outer diameter D2 of the part 2 can be set to about 3.4 mm. The length is set arbitrarily.

(2). Construction condition The drill screw of this embodiment can be used at various sites (structures). For example, as shown in FIGS. 2 (A) and 2 (B), the heat insulating material 17 can be used to hold and fix the heat insulating material 17 to the deck plate 18 (the mating material 10). A circular washer 19 is used for construction, and the washer 19 is provided with a lower constricted tapered receiving seat 19a that overlaps the seating surface of the head 3 of the drill screw. The screw head 3 and the heat insulating material 17 are covered with a waterproof sheet 16.

In the construction, the drill screw enters the heat insulating material 17 by the drilling action of the drilling portion 2 and the screwing action of the screw portion, and then, as shown in FIG. 2C, the drilling portion 2 enters the deck plate 18. The pilot hole 20 is drilled, and then, as the screw thread 4 is screwed in, the pilot hole 20 is expanded by the valley surface 11 to expand the diameter, and the screw thread 4 bites into the inner peripheral portion 21 of the pilot hole 20. Eventually, the head 3 strongly abuts on the washer 19 and the screwing is stopped.

Then, due to the fact that D1 <D2 and E < t , as shown in FIG. 2, first, the inner peripheral portion 21 of the deck plate 18 is crushed and deformed while being tightly fitted to the valley surface 11 of the threaded portion. As a result, the vertical movement (bending deformation) is restricted, and the inner peripheral portion 21 becomes a thick portion 21a due to the movement of the meat due to the forced expansion (diameter expansion).

Further, when the screw portion is screwed, the inner peripheral portion 21 is deformed in the vertical direction at the initial stage of screwing to become a bite portion 21b in which a part of the screw portion has entered (fitted) into the valley portion of the screw portion, and the diameter is expanded in that state. It can be said that by receiving the action, a strong pressing force acts on the portion located on the opposite side of the biting portion 21b with the axial center O sandwiched between them to form the thick portion 21a. That is, when about half of the prepared hole 20 becomes a biting portion 21b that is strongly stretched against the valley of the threaded portion, the inner peripheral portion 21 escapes to the opposite side to the biting portion 21b to form a thick portion 21a. I can say.

This point can be understood from the photographs of FIGS. 3 (B) and 3 (C). In FIGS. 3A and 3B, the upper surface of the deck plate 18 appears, the lower surface of the prepared hole 20 appears, and the lower surface appears in (C), but the upper and lower surfaces are viewed from the axial direction. Marks 22 are placed at the same positions to clarify the positional relationship.

Then, by firmly biting the notch groove 14 of the thread 4 into the thick portion 21a, a high fastening force and a loosening prevention effect are exhibited, and the female screw of the prepared hole 20 is crushed and the screw portion runs idle. It is also possible to prevent the stripping phenomenon that occurs.

Further, in the present embodiment, the advancing side end surface 14b located behind the valley bottom 14a in the notch groove 14 in the screwing direction acts as a cutting edge, so that the force required for screwing can be reduced and the inner peripheral portion can be reduced. The bite of the screw thread 4 into the thick portion 21a of 21 can be made good, and the female screw forming function can be improved. In this case, eight notch grooves 14 are formed, and the height of the adjacent notch grooves 14 in the axial direction is P / 8, so that at least three or four notches are cut within a range of about half a circumference. The notch groove 14 overlaps the inner circumference of the pilot hole 20 in the deck plate 18.

Therefore, the notch groove 14 frequently overlaps with the inner peripheral surface of the prepared hole 20, and the cutting function by the advancing side end surface 14b of the notch groove 14 can be ensured. Although the burr 23 can be seen in FIG. 3, it can be said that the occurrence of the burr 23 in this way is proof that the advancing side end surface 14b of the notch groove 14 functions as a cutting edge. Further, among the notch grooves 14, the chasing side end surface 14c located on the front side in the screwing direction across the valley bottom 14a acts as a resistance against loosening, but the chasing side end faces 14c of the plurality of notch grooves 14 are particularly thick portions. Since the pilot hole 20 is stretched at the location 21a, a high anti-loosening effect can be exhibited.

In addition, the thick portion 21a is elastically deformed to form a female screw, and when the screwing is completed, an elastic restoring force (springback) acts, but the thick portion 21a bites into the notch groove 14 due to the elastic restoring force. Then, the trailing end surface 14c of the notch groove 14 acts as a strong resistance against screwing back.

The notch groove 14 can be formed in a posture parallel to the axis, but if it is formed in a twisted posture as in the present embodiment, it will come into contact with the blade of the die in processing with a rolling die or a flat die. Has the advantage of being smooth and easy to process. That is, since the notch groove 14 can be formed while pressurizing the die with a constant pressure, the processing accuracy can be improved and the durability of the die is also excellent. In particular, if the spiral direction of the notch groove is formed in the same direction as the spiral direction of the thread 4 as in the embodiment, the resistance to the die can be made constant, which is preferable.

As shown in FIG. 2F, the notch groove 14 can be inclined in the direction opposite to the inclination direction of the screw thread 4, but the notch groove 14 is in the same direction as the screw thread 4 as in the embodiment. As shown by the arrow 24 in FIG. 2E, when the drill screw is screwed back (when it is raised), the trailing end surface 14c of the notch groove 14 causes the deck plate 18 to face downward. Since it acts as a push, it is understood that the resistance action against the loosening of the drill screw is promoted . Therefore, it can be said that it is also excellent in the anti-loosening effect.

As shown in FIG. 4C , the thread 4 can also be formed in a grooved manner having two ridges 4a and 4b. In the illustrated example, the notch groove 14 is the follower flank. It is formed only in the place. Although the notch groove 14 reaches the valley surface 11 in the segmentation (C), it may be formed in a state where only the ridge portion on the follow -up side is excised.

The notch groove 14 can be formed so as to divide the entire screw thread 4, but if it is formed only at the trailing flank portion as shown in the figure, the function of pushing the mating materials 10 and 18 into the valley portion is provided. Since it becomes high, the loosening prevention effect can be improved. Further, the notch groove 14 can be formed only at the portion of the leading flank, but if it is formed at the portion of the trailing flank as shown in the illustrated example, the notch groove 14 resists screwing back. Since the function of acting as a screw is enhanced, there is an advantage that the anti-loosening effect can be further improved. When the notch groove 14 is formed at the portion of the chasing flank, the angle θ2 of the chasing flank may be about 5 to 10 °.

FIG. 5 shows an example of a fixing device related to a combination of a drill screw and a washer 19. The drill screw is basically the same as that of the above-described embodiment, and the only difference is that the seating surface 3a of the head 3 has a flat cross-section polygon (octagon). Then, corresponding to the polygonal shape of the seating surface 3a of the head 3 in the drill screw, the receiving seat 19a of the washer 19 also has a flat cross-section polygonal shape (octagonal shape) similar to the seating surface 3a. There is.

In this example, the washer 19 is pushed into the heat insulating material 17 at the end of fastening. Therefore, although the screwing resistance is large, as described above, since the drill screw of the present embodiment has a high fastening force with respect to the deck plate, the washer 19 does not cause the phenomenon that the female screw formed on the deck plate 18 is crushed. Can be strongly pressed against the heat insulating material 17 and screwed firmly.

On the other hand, if the drill screw loosens and tries to rotate after fixing, the ridge line of the seat surface 3a must overcome the plane of the receiving seat 19a. Therefore, when the screw loosens, the washer 19 must compress and deform the heat insulating material 17. However, since the washer 19 has a large area, a large resistance is generated in pushing the washer 19 into the heat insulating material 17, so that a remarkably high anti-loosening effect can be obtained.

When the number of rows of the notch groove 14 and the number of angles of the seat surface 3a and the receiving seat 19a are matched as in the embodiment, the effect of preventing the notch groove 14 from being caught and the square seat surface 3a and the receiving seat 19a are obtained. Since the loosening prevention effect due to the fitting of the above is exhibited at the same time, the loosening prevention effect can be remarkably improved, which is preferable.

In the present embodiment, when the receiving seat 19a is pushed by the ridgeline of the seating surface 3a, the engagement between the seating surface 3a and the receiving seat 19a changes. Therefore, the screwing resistance and the loosening prevention effect increase as the number of angles of the seat surface 3a and the receiving seat 19a decreases. On the other hand, the screwing resistance and the loosening prevention effect also depend on the elastic deformation rate of the work such as the heat insulating material 17. Therefore, the number of angles of the seat surface 3a of the head 3 and the receiving seat 19a of the washer 19 may be set in consideration of the elastic deformation rate of the work such as the heat insulating material 17. Generally, it can be said that the number of angles is preferably about 5 to 10.

Although the embodiments of the present invention have been described above, the present invention can be embodied in various ways. For example, the shape of the thread may be an ordinary triangle, and each dimension can be set according to the application. The drill screw may be pyramidal. It is also possible to form threads into multi- threaded threads (in this case, threads of different heights can be arranged side by side).

Further, the present invention has an excellent form in terms of design in relation to the thread and the notch groove. Therefore, it can also be a target for design registration. In this case, it is possible not only to be registered as a whole design but also to be registered as a partial design. An arbitrary range can be specified as the partial design. For example, as shown by K1 in FIG. 1A, the range sandwiching the tapered portion 12, and as shown by K2, the tapered portion 12 and the straight portion of the threaded portion. As shown by K3, it is possible to specify an appropriate range of only the straight portion of the threaded portion. The notch groove does not have to be V-shaped when viewed from the axial direction, and may be quadrangular or trapezoidal.

The present invention can be embodied in a drill screw, a structure using the drill screw, and a fixing device. Therefore, it can be used industrially.

1 axis 2 drill part (self-drilling part)
3 head 4 thread 8 thread leading flank 9 thread trailing flank 10 mating material 11 valley surface 14 notch groove 14a bottom 14b advancing side end face
14c chasing side end face
17 Insulation material as work 18 Deck plate as an example of structural material (counterpart material) 19 Washer 19a Receiving seat 20 Pilot hole 21 Inner circumference 21a Thick part 21b Biting part

Claims (5)

A drill screw for fixing a work to a thin metal plate with a thickness of 1.6 mm or less.
It includes a shaft having a threaded portion made of a thread, a drill portion provided at the tip of the shaft , and a head provided at the base end of the shaft.
In the threaded portion, a group of notch grooves that divide the thread completely or partially is divided in the circumferential direction to form a plurality of rows , and the notch grooves are formed behind the valley bottom with the valley bottom in between. The position of the advancing side end face functions as a cutting edge for the thin metal plate.
In the threaded portion, a band-shaped valley surface is formed in the valley portion between adjacent threads, and the valley diameter of the threaded portion is larger than the inner diameter of the prepared hole formed in the thin metal plate by the drill portion. While having a large diameter or the same diameter ,
When the width dimension of the valley surface is E, the pitch of the threads is P, and the plate thickness of the thin metal plate is t , the state of being screwed into the thin metal plate by setting E <t <P. Then, on one side sandwiching the axial center, the inner peripheral portion of the thin metal plate fits tightly into the valley portion, and on the other side sandwiching the axial center, the inner peripheral surface of the pilot hole in the thin metal plate. The screw thread is set to bite into the
The axial distance between the notch grooves adjacent to each other in the circumferential direction is smaller than the thickness of the thin metal plate, and in a state where the screw portion is screwed into the thin metal plate, among the threads. At least one notch groove is set to overlap the inner peripheral surface of the pilot hole in the thin metal plate.
Drill screw for thin metal plates. Let θ1 be the angle formed by the plane orthogonal to the axis and the flank on the advancing side of the thread, and θ2 be the angle formed by the plane orthogonal to the axis and the flank on the trailing side of the thread, and the relationship θ1> θ2. And θ1 + θ2 is set to 35 to 45 °.
Further, when the axial distance between the bottoms of the notch grooves in the adjacent threads is L, L and the t are the same or set to t> L.
The drill screw for a thin metal plate according to claim 1. The thin metal plate and the screw thread have a relationship in which a plurality of notched grooves exist within a range of the thickness of the thin metal plate within a half circumference in a state where the threaded portion is screwed into the thin metal plate. Is set to
The drill screw for a thin metal plate according to claim 1 or 2. It is provided with a structural material made of a thin metal plate having a thickness of 1.6 mm or less, a work that overlaps the structural material , and a drill screw that presses and fixes the work to the thin metal plate.
The drill screw includes a shaft having a screw portion made of a screw thread, a drill portion provided at the tip of the shaft , and a head provided at the base end of the shaft, and the screw portion has a screw thread. A group of notch grooves that divide the whole or a part of the notch groove is divided in the circumferential direction to form a plurality of rows , and the advancing side end face of the notch grooves located behind the screwing direction across the valley bottom is the thin portion. It has a structure that functions as a cutting edge for a metal plate .
In the threaded portion, a band-shaped valley surface is formed in the valley portion between adjacent threads, and the valley diameter of the threaded portion is larger than the inner diameter of the prepared hole formed in the thin metal plate by the drill portion. While having a large diameter or the same diameter,
When the width dimension of the valley surface is E, the pitch of the threads is P, and the plate thickness of the thin metal plate is t , the state of being screwed into the thin metal plate by setting E <t <P. Then, on one side sandwiching the axial center, the inner peripheral portion of the thin metal plate fits tightly into the valley portion, and on the other side sandwiching the axial center, the inner peripheral surface of the pilot hole in the thin metal plate. The screw thread is set to bite into the
The axial distance between the notch grooves adjacent to each other in the circumferential direction is smaller than the thickness of the thin metal plate, and in a state where the screw portion is screwed into the thin metal plate, among the threads. At least one notch groove is set to overlap the inner peripheral surface of the pilot hole in the thin metal plate.
Structure. It is composed of the drill screw and the washer according to any one of claims 1 to 3, and the seating surface of the head of the drill screw is formed in a tapered shape with a narrowed lower portion and a polygonal shape with a flat cross section. On the other hand, the washer is formed with a flat cross-sectional polygonal lower constricted tapered receiving seat in which the seating surface of the head of the drill screw is in close contact, and the receiving seat is peripheral without being divided by a slit. A series of continuous directions,
Fixing device for thin metal plates.

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